The new Indo-Pacific security pact between the US, UK and Australia is an “insult to a Nato partner” and US president Joe Biden is treating allies in the same way his predecessor Donald Trump did, according to German chancellor Angela Merkel’s longtime foreign policy adviser.

Christoph Heusgen told the Financial Times that the new security alliance, dubbed Aukus, had led to a “big loss of trust” in the Biden administration. “And I don’t know whether that loss has been sufficiently outweighed by the supposed increase in regional security,” he added.

Heusgen’s comments mark Germany’s political establishment’s most stinging public rebuke of the US over the Aukus affair. Publicly Merkel’s government has been restrained in its criticism of Washington, although in private, officials have expressed solidarity with Paris.